The present invention relates to a lot supply system and lot supply method and, more particularly, to a lot supply system and lot supply method suitably applied to a production line where material processing in a clean atmosphere is required as in the pre-process of semiconductor device manufacture.
Conventionally, various types of lot supply systems have been developed in which a product lot is supplied to a unit in a processing step, the lot is recovered after it is processed by the unit in the processing step, and the recovered lot is supplied to a unit in a measurement step.
As a prior art of lot supply described above, for example, a technique described in xe2x80x9cSemiconductor Production Systemxe2x80x9d, Japanese Patent Laid-Open No. 10-116875 (reference 1) is proposed. The semiconductor production system of reference 1 aims at shortening a period of time for production of semiconductor wafers, and comprises a plurality of processing units for processing semiconductor wafers in a lot, a stocker for storing a lot except the lot in process in the processing units, and a plurality of non-processing units provided in association with the stocker to perform either one of inspection, measurement, and foreign matter removal, other than processing of the semiconductor wafers in the lot. According to this system, non-processing of the semiconductor wafers in the lot is performed by the non-processing units while the lot is stored in the stocker.
The prior art described above has the following problems.
In the conventional lot supply system, as described above, the product lot is supplied to the unit in the processing step, the lot is recovered after it is processed by this unit, and the recovered lot is supplied to the unit in the measurement step. Since the measurement step is not generally automated, it requires manual operation. Hence, in the measurement step, every time measurement operation is performed, the operator need access the product lot. In particular, in the manufacturing process of semiconductor wafers and the like, dust from the operator influences the product lot to interfere with an increase in product yield.
It is an object of the present invention to provide a lot supply system and lot supply method in which the product lot is protected from dust from an operator so that the product yield is increased.
In order to achieve the above object, according to the present invention, there is provided a lot supply system comprising a plurality of processing units for outputting a lot supply request and performing a predetermined process for a lot supplied thereto, a lot supply unit for supplying a lot stored therein to requesting processing units in response to the lot supply request from the processing units, a plurality of counting means for counting product lots supplied to the requesting processing units at least in units of the requesting processing units, and supply control means for, when counts of the counting means reach preset values set in units of the requesting processing units, supplying measurement lots stored in advance to the requesting processing units and initializing counts of the counting means.